This invention relates to an apparatus for controlling an internal combustion engine having a plurality of cylinders and fuel injectors provided to inject fuel in a sequential fashion for the respective cylinders and, more particularly, to an engine control apparatus for performing fuel injection twice from each of the fuel injectors to supply fuel in an amount required in one combustion phase of the associated cylinder.
For example, Japanese Kokai No. 61-76143 for Utility Model Registration discloses a fuel control apparatus where fuel injection is made twice to supply the amount of fuel required for each cycle of operation of an engine cylinder. For this purpose, the engine control apparatus calculates a value for the amount of fuel injected from a fuel injector during the first fuel injection according to the engine operating conditions existing at a time just before the first fuel injection is initiated and a value for the amount of fuel injected from the fuel injector during the second fuel injection according to the engine operating conditions existing at a time just before the second fuel injection is initiated. During transition of the engine operation where the engine load is increasing or decreasing, however, the sum of the amount of fuel injected during the first fuel injection and the amount of fuel injected during the second fuel injection is less or greater than the amount of fuel required at the time when the injected fuel is charged in the associated cylinder. Therefore, such a conventional fuel control apparatus fails to provide good fuel control during transition of the engine operation.